“The water was as clear as glass – when the drains were cleaner – till 20 years ago. A coin fallen in [to the bottom of the river] could be seen from above. We could drink directly from the Yamuna,” says fisherman Raman Haldar, scooping a cupped palm into the muddy waters, bringing it near his mouth to emphasise the point. Seeing our mortified look, he lets it run down his fingers with a wistful laugh.

In today’s Yamuna, plastics, foil wrappers, muck, newspapers, dead flora, concrete debris, cloth scraps, slush, rotting food, wandering coconuts, chemical foam and water hyacinth offer up a dark reflection of the capital city’s material and mythical consumption.

Just 22 kilometres (or barely 1.6 per cent) of the Yamuna flows through the National Capital Territory. But the wastes and poisons emptied into that little stretch account for close to 80 per cent of all pollution in the 1,376 kilometre river. Acknowledging that, the monitoring committee report of the National Green Tribunal (NGT) in 2018 pronounced the river in Delhi a 'sewer line'. The resulting severe depletion of oxygen levels in the water causes large-scale deaths of fish.

Last year, thousands of fish were found dead at the Kalindi Kunj Ghat on the southern stretch of the river in Delhi, and other aquatic life have become a near-annual occurrence in the Delhi stretch of the river.

“For a river ecosystem to survive, it needs a dissolved oxygen (amount of oxygen in water) level of 6 and above. Fish require a DO level of at least 4-5. In the Delhi part of Yamuna, the DO is between 0 to 0.4,” says Priyank Hirani, director of the Water-to-Cloud project of the Tata Centre for Development at the University of Chicago. The project maps real-time pollution in rivers.